Which statement about DNS caching is true?

Which statement about DNS caching is true?

• A. DNS caching reduces query traffic and speeds up future lookups.
• B. DNS caching permanently stores DNS records for all domains.
• C. DNS caching prevents any DNS queries from reaching servers.
• D. DNS caching requires each query to be paid for.

Answer: (A)

DNS caching works by keeping recently resolved domain-to-IP mappings in a local cache for a limited time, known as the TTL. When you try to visit a site again, the resolver can answer from this cache without asking the broader network, so lookups are faster and generate fewer requests across the internet. That’s why the statement that caching reduces query traffic and speeds up future lookups is the best choice: it captures both the efficiency gain in time and the reduction in network traffic. A cache entry isn’t permanent; after the TTL expires, the cached information is considered stale and the resolver must re-query authoritative DNS servers to refresh it. This keeps data up to date while still benefiting from fast responses in the meantime. Caching doesn’t stop all DNS queries from reaching servers—only misses or expired entries trigger new lookups. And there’s no payment involved for DNS caching.

DNS caching works by keeping recently resolved domain-to-IP mappings in a local cache for a limited time, known as the TTL. When you try to visit a site again, the resolver can answer from this cache without asking the broader network, so lookups are faster and generate fewer requests across the internet. That’s why the statement that caching reduces query traffic and speeds up future lookups is the best choice: it captures both the efficiency gain in time and the reduction in network traffic.

A cache entry isn’t permanent; after the TTL expires, the cached information is considered stale and the resolver must re-query authoritative DNS servers to refresh it. This keeps data up to date while still benefiting from fast responses in the meantime. Caching doesn’t stop all DNS queries from reaching servers—only misses or expired entries trigger new lookups. And there’s no payment involved for DNS caching.